If My Knees Hurt, Does That Mean I’m Growing?

Knee pain in a child or teenager does not reliably mean they are in the middle of a growth spurt. The label “growing pains” has stuck around since the 1820s, but no research has ever confirmed that the pain correlates with periods of rapid growth, and classic growing pains typically strike the muscles of the legs rather than the knee joint itself. That said, growth does create real biomechanical stress on a developing knee, and several common conditions tied to skeletal immaturity produce pain right around the kneecap. The relationship between knee pain and growing is real but far more complicated than the folk explanation suggests.

What “Growing Pains” Actually Are

The term dates back to the French physician Marcel Duchamp, who first described a pattern of recurrent leg pain in young children. Despite the name, researchers have never found evidence linking these episodes to periods of especially rapid growth. That disconnect has led some clinicians to propose alternative names like “benign nocturnal limb pains of childhood,” though “growing pains” persists because it doesn’t imply a specific disease and highlights that the pain happens during childhood, the age when these episodes are most common.¹

Classic growing pains have a recognizable pattern. They affect the muscles of the thighs, calves, or shins, not the joints. They tend to show up in the late afternoon or evening, sometimes waking a child in the middle of the night, and are gone by morning. There is no swelling, no redness, no limping. If a child’s pain is inside or around the knee joint, that alone is a clue that something other than textbook “growing pains” is going on. Joint-localized pain, stiffness, or swelling could point to conditions ranging from inflammatory arthritis to anatomic problems like a meniscal tear.²

How Growth Spurts Indirectly Cause Knee Pain

Even though growing pains themselves aren’t joint pains, a rapid growth spurt does set the stage for knee trouble. During puberty, bones can lengthen faster than the surrounding muscles and tendons can adapt. The quadriceps-patellar tendon complex, which runs down the front of the thigh and attaches below the kneecap, is a common site where this mismatch shows up. The soft tissue essentially falls behind the femur’s growth, creating a temporary loss of flexibility that puts extra strain on the tendon’s attachment points around the knee.³ That strain is why adolescents in a growth spurt, especially those who are physically active, face a higher risk of overuse injuries in the knee and elsewhere.⁴

So there is a kernel of truth buried in the idea that knee pain means you’re growing. Growth doesn’t cause the pain directly, but the mechanical imbalance that comes with fast bone growth makes several painful knee conditions more likely. The specific conditions worth knowing about deserve their own discussion.

Osgood-Schlatter Disease

If you’re a teenager with a painful, bony bump just below the kneecap, Osgood-Schlatter disease is the usual suspect. It involves inflammation of the tibial tubercle, the small bony prominence at the top of the shinbone where the patellar tendon attaches. It is especially common in athletic adolescents whose growth plates are still maturing during puberty.⁵ Running, jumping, and kneeling make it worse because those motions load the tendon right where it pulls on the still-developing bone.

The condition is typically self-limiting, meaning it goes away once the growth plate closes and the bone hardens. But “self-limiting” can be misleading. A Danish cohort study following people who had Osgood-Schlatter as adolescents found that about 85 percent still had a noticeable bony bump at the tibial tubercle in adulthood, and roughly three-quarters reported ongoing pain or problems in the same area.⁶ That complicates the reassuring “you’ll grow out of it” narrative many teens hear. While most people do fine functionally, the idea that the condition vanishes without a trace isn’t quite right.

Sinding-Larsen-Johansson Syndrome

A close relative of Osgood-Schlatter, Sinding-Larsen-Johansson syndrome targets the other end of the same tendon, where the patellar tendon connects to the bottom of the kneecap. It shows up as localized knee pain in physically active adolescents, with boys affected more often. The condition generally responds well to conservative treatment, particularly limiting activity, rest, icing, gentle stretching, and over-the-counter anti-inflammatories. Most cases resolve within two to eight months.⁷

Both Osgood-Schlatter and Sinding-Larsen-Johansson are “apophyseal” injuries, meaning they happen where a tendon pulls on a growing bone. These are the conditions most honestly tied to the phrase “my knees hurt because I’m growing.” The growth plate hasn’t finished hardening yet, so the tendon’s pull during sports and activity can irritate or even partially separate the bone at the attachment site. Once skeletal maturity arrives and those attachment points solidify, the mechanical vulnerability disappears.

Patellofemoral Pain Syndrome

The single most common cause of knee pain in adolescents isn’t one of the apophyseal conditions above. It’s patellofemoral pain syndrome, sometimes called “runner’s knee” or “anterior knee pain.” This involves pain around or behind the kneecap, worsened by stairs, squatting, or sitting for long stretches. It typically begins around age 11, coinciding with the start of puberty, and girls are affected at roughly twice the rate of boys. In young female athletes exposed to high repetitive loads, like basketball players, the prevalence can reach around 16 percent.⁸

The causes are multifactorial. Rapid bone growth, muscular imbalance around the hip and thigh, and the biomechanical changes of puberty all contribute. This is where the “growing” connection is indirect but genuine: the same skeletal changes that define a growth spurt alter the tracking and loading of the kneecap. But the pain isn’t caused by bones lengthening. It’s caused by the altered mechanics that follow from lengthening.

Joint Hypermobility and Knee Pain

Some children have joints that are naturally more flexible than average, a trait called joint hypermobility or ligamentous laxity. This is increasingly recognized as a contributor to a range of musculoskeletal complaints in kids, including growing pains, anterior knee pain, and recurrent limb soreness.⁹ In one study of children referred to a clinic for hypermobility-related symptoms, 92 percent had hypermobile knees specifically, making the knee joint the most frequently affected site.¹⁰

Hypermobility isn’t something you grow out of the way you grow out of Osgood-Schlatter. It’s a structural trait, often inherited, and it can continue to cause joint discomfort into adulthood if the muscles around the joint aren’t strong enough to compensate for the extra range of motion. A child with hypermobile knees and growing pains might assume the pain is from growing, but the underlying issue is laxity, not lengthening. Strengthening exercises, particularly around the quadriceps and hips, tend to help more than waiting for the growth spurt to end.

Flat Feet and Knee Pain in Kids

Foot shape can influence what happens further up the leg. Children with a flatter foot posture are more likely to experience pain or discomfort at the knee, hip, and back compared to children with a more arched foot.¹¹ The mechanism isn’t fully settled; the association exists, but the biomechanical theories explaining exactly how a flat foot leads to knee pain haven’t been consistently confirmed. Still, it’s worth noting because flat feet are extremely common in younger children and often go unrecognized as a potential factor in knee complaints. If a child’s knee pain doesn’t fit any of the classic patterns, an evaluation of their foot mechanics might reveal a contributing factor.

When Knee Pain Comes from Somewhere Else

One of the less intuitive things about pediatric knee pain is that it doesn’t always originate in the knee. Hip problems, in particular, can refer pain to the knee in children. A case report describes a seven-year-old boy who presented with recurring knee pain. His knee exam, blood work, and knee X-rays were all normal, but imaging of the hip revealed a defect in the femoral head and increased fluid in the hip joint.¹² The takeaway for parents and pediatricians is that when a child’s knee pain has no clear explanation after examining the knee, the hip should be checked. This phenomenon of referred pain is well recognized but still catches people off guard.

Conditions That Require More Attention

Most adolescent knee pain is mechanical and resolves with time, activity modification, and basic strengthening. But some causes need earlier intervention.

Juvenile idiopathic arthritis (JIA) is an inflammatory condition where the immune system attacks the joint lining. The knee is the most commonly affected joint, and many children with JIA experience significant disability there. In one study of 38 children with JIA, about 40 percent had acute knee inflammation and the remaining 60 percent had chronic knee involvement.¹³ JIA looks different from mechanical knee pain: there’s usually morning stiffness, visible swelling, and sometimes warmth over the joint. It doesn’t go away with rest the way overuse conditions do.

Osteochondritis dissecans is another condition that deserves mention. It involves a piece of cartilage and underlying bone in the knee losing its blood supply, which can cause pain, catching, or locking of the joint. Most cases in children present as stable lesions that respond to rest and restricted activity, but unstable fragments sometimes require surgery.¹⁴ The cause isn’t well understood, and the condition’s natural history is hard to predict, which makes follow-up imaging important when it’s suspected.

Red Flags Worth Knowing

Not every episode of knee pain warrants a doctor’s visit. Mild aching after a long day of running around, in a child who is otherwise fine and has no swelling, is unlikely to be anything worrisome. But certain features should prompt a medical evaluation. International guidelines recommend imaging when there is suspected fluid in the joint, limited range of motion, pain with palpation, inability to bear weight, mechanical symptoms like the knee catching or locking, or pain that persists despite initial treatment.¹⁵

A practical checklist for parents:

• Location: Pain in the muscles (thighs, calves) that comes and goes at night and resolves by morning fits the classic growing-pains pattern. Pain localized to or around a joint is a different story.
• Swelling or warmth: Growing pains never cause visible joint swelling. If the knee looks puffy or feels warm, something inflammatory or structural is happening.
• Limping: A child with growing pains walks normally. A limp means the pain is affecting function enough to warrant evaluation.
• Morning stiffness: Stiffness that lasts more than 15 to 30 minutes after waking is a hallmark of inflammatory arthritis, not mechanical pain.
• Single joint: Growing pains typically affect both legs. Persistent pain in one knee only is more suspicious for a local problem.

The Vitamin D Connection

An emerging area of research involves vitamin D and its role in growing pains. Vitamin D is critical for bone growth and mineralization, and one theory holds that deficiency allows the bone’s collagen matrix to expand outward, pressing on pain-sensitive nerve fibers on the bone surface.¹ A study of children with growing pains and low vitamin D levels found that after supplementation, pain intensity dropped substantially, with average pain scores falling by more than half.¹⁶

This doesn’t mean every child with aching legs needs a vitamin D test, and it certainly doesn’t mean vitamin D deficiency is the sole explanation for growing pains. But for children with frequent, bothersome limb pains, checking a vitamin D level is a low-risk step that might turn up a correctable problem. The relationship also underscores how growing pains are likely driven by multiple overlapping factors rather than a single cause.

Why the Myth Persists

The “your knees hurt because you’re growing” explanation is so durable partly because it’s half true. Knee pain in children and adolescents really does cluster during growth spurts. Osgood-Schlatter, Sinding-Larsen-Johansson, and patellofemoral pain all peak during puberty, when bones are lengthening fastest. The timing makes the connection feel obvious, even though the mechanism is more about biomechanical mismatch than about growth itself.

There’s also a comforting simplicity to the explanation. Telling a child “your bones are growing faster than your muscles” offers a clear narrative with a built-in reassurance: the pain will stop when you stop growing. For many adolescents with apophyseal conditions, that’s roughly accurate. But it can become a problem if the explanation is applied too broadly, because it may delay evaluation of conditions that need actual treatment, like JIA, osteochondritis dissecans, or a hip problem masquerading as knee pain. The best approach is to take the growth-spurt connection seriously as a starting framework and then look more carefully when the details don’t fit the pattern.